Things can change in two years, but the way the Republican Party is currently operating, primary challenges like this are nearly impossible to defeat. Christine O-Donnell won, and she was pretty obviously a totally underqualified borderline nutcase. Maine looks like a prime pick-up opportunity for Democrats in 2012. If I'm Snowe, I'm figuring my best chance to retain the seat is not to try to lurch to the right -- which hasn't worked for anybody; these activists have long memories -- but to make a plan to hold the seat as an independent or Democrat. The chances of surviving that way are way higher than the chances of making it through a Republican primary.
"If you have a problem, go meditate or go on a vacation. Don't think about it."